Note: Descriptions are shown in the official language in which they were submitted.
This lnvention relates to used containers
fabricated at least in part from difEererlt metals or alloys,
and more particularly, this invention relates to a method or
process for reclamation of used containers, such as be~erage
containers, in a manner which permits recovery or
segregation of container components substantially in
accordance with their compositions, for example, or
composition types.
In the packaging or container field, such as -the
used beverage containers having at least one or more
components thereof fabricated from aluminum alloys, there
has been ever-increasing interest and extensive research
into methods of reclaiming the aluminum components. The
interest has been precipitated by the importance of
conserving resources and caring for environmental problems.
However, heretofore recycling such materials has been
greatly hampered by the lack of a method which would be
economically attractive. For example, attempts to recycle a
beverage can having a body fabrica-ted from one aluminum
alloy and a top or lid constructed from a different aluminum
alloy often results in an aluminum melt having the
composîtion of neither alloy. Such melt greatly decreases
in value because i-t does not readily lend i-tself to reuse in
the can body or lid without major dilutions, p-urifications
and realloying or other modifications. That is, it can be
seen that there is a great need for a method of recycling
containers of the type, for example, described wherein the
different components thereof are recovered and segregated
according to alloy or according to alloy type.
The problem of segrega-tion of different alloys is
,P~D~
recognized in U.S. Patent 3,736,896, where there is
disclosed the separating of aluminum alloy tops or lids from
steel bodied cans by me'lting a small 'band of aluminum around
the periphery of the can body to provide a separating area
allowing separation of the aluminum end from the steel
cylindrical body. In this disclosure, induction heating is
used to melt the band wherein an encircling inductor
surrounds a bead and is connected to a high frequency power
supply. However 9 this approach seems to presume that a used
beverage can is not crushed and the end remains perfectly
circular. Further, to melt the ends off in this manner
would not seem to be economical since the ends would have to
be removed individually.
In U.S. Patent 4,016,003, containers having
aluminum alloy 'bodies and lids are shredded to particles in
the range of l to 1-1/2 inch and then su'bjected to
temperatures of around 700F to remove paints and lacquers.
ln addition, U.S. Patent 4,269,632 indicates that since the
conventional alloys for can ends, e.g., Aluminum Association
(AA alloy) 5182, 50~2 or 5052, and for can bodies, e.g., ~A
3004 or AA3003, differ significantly in composition, and in
the manufactured can, the end and body are essentially
inseparable, and that an economical recycle system requires
the use of the entire can. U.S. Patent 4,269,632 further
notes that the recycling of cans results in a melt
composition which differs significan-tly from the
compositions of both the conventional can end and can body
alloys. In this patent, it is sugges-ted that bo-t'h can end
and body be fabricated from the same al,loy to obviate the
recycling problem. With respect to can ends and bodies made
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5~
from AA5182 and 3004, it is indicated -that normally pure
aluminum must be added regardless of the alloy prepared.
In view of these proble~ls with recycling metal
containers, such as aluminum beverage containers having
components thereof comprised of different alloys, it would
be advantageous to have a method which would permit recovery
of the containers by segregating the components thereof
according to their a]loys or segregating the components
lo according to their alloy type. That is 9 by segregation of
the components prior to melting, the components can be
melted and refabricated in accordance with normal procedures
without, inter alia, expensive dilutions or purification
steps.
An object of this invention is to provide a
feedstock comprised of said metallic components, said alloys
having different incipient melting temperatures.
Another object of the present invention is to
shred said feedstock and thereafter screen to remove fines
therefrom having at least sizes in a size range of the
fragment component.
Yet another object of the present invention is to
heat the feedstock to effect incipient melting of the
component having the lowest incipient melting temperature
and agitate sufficiently to cause the component having the
lowest incipient melting temperature to fragment.
And yet another object of the present lnvention is
to segregate the fragmented components from the unfragmented
feedstock.
These and other objects will become apparent from
the drawings, specification and claims appended hereto.
~ ~,,r~5~
In accordance with these objects, there is disclGse~
a method of detaching and segregating me-tallic components
secured to metallic articles, the segregation being made in
accordance with with alloy composition of the componen-ts. The
method comprises the s-teps of providing articles having at
least two components thereon comprised of different aluminum
alloys and heating the articles to a temperature sufficiently
high to initiate incipient melting of -the component having the
lowest incipient melting temperature. While the articles are
held at or slightly above the lowes-t incipient melting
temperature of said aluminum alloy componen-t, they are subjec-ted
to agitation sufficient to cause the aluminum alloy component
having the lowest incipient melting tempera-ture l~o fracture and
detach itselE from the article.
According -to one aspect of the present invention there
is provided in a process of fragmenting and segregating shredded
metallic components fabricated from different aluminum alloys in
which a fragmented component is provided, a me-thod of removing
fines for purposes of enhancing segregation of -the alloys, the
method comprising the steps of: (a) providing a feeds-tock
comprised of said metallic components, said alloys having
different incipient melting temperatures; ~b) shredding said
feedstock; (c) screening said shredded feedstock to remove
fines -therefrom having at least sizes in a size range of the
fragment component; (d) heating the feeds-tock to effect incipi-
ent melting of the componen-t having the lowest incipient melting
temperature; (e) agitating said heated feedstock sufficien-tly
to cause said component having the lowes-t incipien-t melting
temperature to fragment; and (f) segrega-ting said fragmented
components from -the unfragmented feedstock.
According to ano-ther aspec-t of the present invention
5~
there is provided in a process of fragmenting and segregating
shredded metallic containers fabricated from different aluminum
alloys in which a fragmented componen-t is provided, a method of
removing fines for purposes of enhancing segrega-tion oE the
alloys, the method comprisirg the steps oE: (a) providing a
feedstock comprised of said metallic containers, said alloys
having different incipient melting temperatures; (b) shredding
said feedstock; (c) screening said shredded feedstock and
removing 1 to 15 wt.% of said feedstock as fines therefrom,
the fines having at least sizes in a size range of the fragment
component; (d) heating the feedstock to effect incipien-t melt-
ing of the component having the lowest incipient melting
temperature; (e) agitating said heated feedstock sufficiently
to cause said component having the lowest incipient melting
temperature to fragmen-t; and (f) segregating said fragmented
components from the unfragmented feedstock.
Thereafter, the fractured and detached components
are segrega-ted from the articles and recovered.
Figure 1 is a flow sheet illustrating steps which
~0 can be used in removing fines in a process for recycling used
aluminum containers.
Figure 2 is a bar graph showing the particle size
distribution of materiaL entering and exiting the furnace at
a temperature of 1060F.
Figure 3 is a bar graph showing the par-ticle size
distribution of material entering and exiting the furnace at
a temperature of 1080F.
Figure 4 is a bar graph showing the particle size
distribution of ma-terial entering and exiting the furnace a-t
a temperature of 1100F.
Figure 5 is a bar graph showing -the par-ticle size
- 4a -
~ 5 ~
distribution of material entering and exiting the furnace at
a temperature of 1120F.
Referring to the flow sheet, used articles from
which the aluminum alloy components are to be recovered or
reclaimed may comprise containers such as food and beverage
containers. Containers to which the process is suited are
used beverage containers comprised of two different aluminum
alloys, From the flo~ sheet, it will be noted that the
articles to be recovered may be subjected to preliminary
sorting to remove ~aterials which would contaminate the
aluminum alloy to be recovered. For example, it would be
desirable to remove glass bottles and steel cans such as
used :Eor food, for example. Further, it is desirable to
remove other materials such as dirt and sand, etc., in order
to cut do~l on the amount of silicon, for example, that can
occur in the reclaimed alloy. Elimination of these
materials can permit use of the alloy reclaimed in
accordance with the present invention without further
purification procedures. The removal of steel
preliminarily, as may be present in the form of containers
or cans or other sources, aids in keeping the iron in the
reclaimed alloy to a level which does not adversely affect
the reclaimed alloy properties.
When the materials to be reclaimed are food or
beverage containers, these are normally packaged in bales
for shipping purposes and, therefore, prior to the sorting
step, the bales would normally be broken apart to remove the
foreign materials.
The bales may be subjected to a shredding type
operation for purposes of breaking them apart. ~fter -the
51~
shredding operation, the feedstock should be screened for
purposes o~ removing metal fines Eor purposes set forth in
detail hereinbelow. As shown in Figure 1, the fines may be
~ubjected ~o a delacquering step and then recombined with a
compatible fraction of the feedstock in accordance with the
invention and eventually melted.
After the shredding and screening step, the
shredded feedstock can be subjected to a delacquering step.
This may be accomplished by solvent or thermal treatments.
The delacquering removes the coatings, such as decorative
and protective coatings, which can contain elements such as
titanium which in high levels is not normally desirable in
the aluminum alloys being reclaimed. When solvent
delacquering is used, it is usually desirable to shred or
pierce the containers in order to permit the solvent to
drain therefrom. When the coatings are removed by thermal
treatments~ the temperature used is normally in the range of
600 to 1000F.
In the ne~t step of the process, particularly
where the containers are used beverage containers having
bodies formed from Aluminum Association alloy (AA) 3004 and
having lids formed from M5182, for example, the containers
are heated to a temperature at which the AA5182 lid becomes
fracture sensitive. This temperature has been found to
correlate closely with the incipient melting or grain
boundary melting temperature of the alloy.
Thus, in reference to used beverage contaîners,
this is the incipient melting temperature of A~5182. By the
use of incipient melting or grain boundary melting
temperature herein is meant the lower temperatures o~ the
P5~
melting range or phase melting range and sligh~ly below at
which the alloy develops or significantly increases in
fracture sensitivity or a-t which fragrnentation of the alloy
can be made to occur wi-thout the use of great force. That
is, in the fracture sensitive condition, fragmentation can
be made to occur by the use of a ~umbling action or falling
action, and the use of forces such as would be obtained by a
hammer mill or jaw crushers are not required. Forces such
as encountered with a hammer mill or jaw crusher are
detrimental to the instant process since they act to crush
the containers, for example, thereby trapping material to be
separated. It will be appreciated that many alloys have
different incipient melting temperatures. For example,
AA3004 has an incipient melting temperature of about 1165F
and ~A5182 has an incipient mel~ing temperature of about
1077F ancl has a phase melting range of about 1077F to
1178F. However, it will be appreciated -that this range can
vary depending to a large extent on the exact composition of
the alloy usedO Incipient or grain boundary melting of the
alloy greatly reduces its strength and sets up the fracture
condition. Thus, the M5182 lids can be detached or removed
from the AA3004 bodies because of the lids being provided in
a condition which makes i-t highly sensitive ~o fracture and
fragmentation. While in this condition, energy, e.g.,
tumbling action~ can be applied for purposes of de-taching or
removing the lid from the can body. The detaching resul~s
primarily from the lid fracturing or fragmenting -to provide
lid particles which are not only smaller than the can body
but generally smaller than a lid.
Thus, after the detaching step, there results a
charge or mass comprised of can bodies and fragrnented lids,
the can bodies being comprised of an alloy or material
different from the fragmented lids, the fragmented lids
having a particle size dis~ribution substantially different
frorn the can bodies. Thus, 1~ can be seen -that not only is
i-t important to remove the lid from the can body, but the
lid fragments must have a particle size which ls
substantially dif:Eerent from the can body. For purposes of
obtaining a product or alloy which is not adversely con~.ami-
nated with the alloy with which it is commingled, the charge
is subjected to a treatment for purposes of classifying or
segregating the particles. When this aspect of the process
is carried out, the result is lid fragments or values
comprised of substantially the same alloys which are segre-
gated from the can bodies.
While the process has been described in general
terms with respect to reclamation of used beverage cans, it
should be understood that the feedstock for the process is
not necessarily limited thereto. That is, the process is
capable of classifying aluminum alloys, particularly wrough-t
alloys, where one of the alloys can be made fracture
sensitive or put in a condition where one of -the alloys can
be fragmented preferentially in order to obtain a particle
size dis-tribution which is different from the particle sizes
of the other alloys. In this way, a partition of the alloys
can be made. Thus, for example, the feed stock for
reclamation may be comprised of used beverage containers
having bodies fabricated from AA3004 and lids fabricated
from AA51820 Other alloys which may be used for llds
include M5082, 5052 and 5042 (Table X). However, other
alloys which ~lay be used for food or beverage can bodies
include alloys such as M3003, AA3104, AA50~2 and AA5052
(Table I~). If such alloys are high in magnesium, for
example, it is required that such can bodies be fractured or
fragmented sufficiently to enable them to be classified with
the lid alloys, such as AA5182. Thus, it will be understood
that the process of the present invention is not only
capable of removing and classifying lids from can bodies, as
noted herein, but it is also capable of classifying the
alloys in the can bodies with the lids when the alloys are
of similar composition and which respond in a similar manner
with respect to fracture or fragmentation characteristics,
as explained herein.
In addition, where the containers have bodies and
lids fabricated from the same alloy, that too may be
reclaimed by classifying in accordance with the present
invention. For example, if can body and lids are fabricated
from sheet having the composition 0.1-1.0 wt.% Si, 0~01-Oo9
wt~% Fe, 0.05-0.4 wt.% Cu, 0.4 to 1.0 wt.% Mn, 1.3-2.5 wt.%
Mg and 0-0.2 wt.% Ti, the remainder aluminum, this would be
classified in accordance with the invention. That is, if
the feedstock to be reclaimed comprises used containers
fabricated from mixed a]loys such as 3004, 5182, 5042, as
well as the can body and lid alloy above, this alloy would
be expected to be classified with the AA3004 body stock
because no incipient melting would occur when -the
temperature was sufficiently high to cause fracture of
AA5182 or AA5042.
I.ikewise, if steel containers having 5182 lid
attached thereto are present in the feedstock, the lids can
be classi~ied in accordance wlth khe invention and the steel
bodies would be recovered with 300l~ can bodies. The steel
container bodies can be separated from the aluminum alloys
with which they may be classified by magnetic separation
eans, for example, aEter the lids have been removed. IE
the steel bodied containers had lids which fractured at
temperatures in the AA300~1 incipient melting range, then it
would be necessary to heat the containers to a higher
temperature as compared to AA5182 to effect a separation of
the lid from the steel body after which the steel bodies
could be removed by magnetic separation, for example.
From the above, it will be seen that the process
of the present invention is rather insensitive to the
aluminum feedstock being recovered. That is, the process is
capable of handling most types of aluminum alloys and is
particularly suited to recovering and classifying wrought
alloy products such as is encountered in used containers.
If the scrap were comprised of aluminum alloys used in
automobiles, for e~ample, AA6009 and AA60l0, as described in
U.S. Patent 4,082~578 herein incorporated by reference,
where the use can be hoods and doors, etc., it may be
desirable to subject such articles to a shreddlng action to
provide a generally flowable mass. Or in recovering ~A2036
and AA5182 from used automobiles, it may be desirable to
shred such products and then effect a separation, as noted
herein.
~ith respect to grain toundary melting or
incipient melting oE one oE the aluminum alloy components to
effect fracture sensi~ivlty or fragmentation, it will be
understood that this is an important step of -the process and
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must be carried out with a certain amount of care. ~sing
the used beverage cans as an example again, it will be noted
that -temperature control is important in this step. That
is, if the temperature is permitted to get too high,
substantial melting of the A~5182 lid can occur, which can
result in losses with respect to aluminum and magneslum
because of oxidation. Temperatures which bring about
substantial melting of the metal normally should be avoided
for the addi~ional reason that it can result in coagulation
of particles with mol-ten aluminum to form a mass which is
not readily flowable when compared to finer discrete
particles. Further, molten aluminum can stick to the
furnace and start bullding a layer of metal and particles
therein which, of course, interferes with the efficiencies
of the whole operation. Also, classification of the
congealed mass becomes much more difficult, if not
impossibleO Lastly, on me:Lting, fines such as sand, glass,
dirt and pigments or contaminants such as silicon o~ide,
titanium oxide and iron oxide tend to become embedded i.n the
molten metal, further making separation thereof difficult.
Thus, in view of the above, it can be seen why temperatures
which result in substantial melting o~ one of the aluminum
alloy components should be avoided.
Likewise, when temperatures are employed which are
too low, the fracture sensitivity o~ the lids drop
dramatically and resistance to fragmentation increases
substantially with the result that separation becomes
extremely difficult and often segregation camlot be
effected. ~ccordingly, it will be seen that it is important
to ha~e the temperature sufficiently high in order to remove
~ ~ h,~{~
the lid from the can 'body. For lids formed from M5182~
this temperature correlates to about the incipient melting
temperature which is about L077F. The me:lting range for
AA5182 is about 1077 to 1178F'. Thus, i the used beverage
containers ar~ heated to 1100F, this is well below the
melting range of AA3004 tabout 1165-1210F) and the lids can
be detached or removed without fracturlng the can bodies.
With respect to grain boundary or incipient
melting~ it will be understood that because the sheet from
which the lids are fabricated has been rolled to a thin
gauge, grains are not well defined. However, i-t is believed
that recrys-tallization occurs when the used beverage
containers are heated~ for example, to remove lacquer, which
can occur at 850F, for example. Thus, grain boundary
melting can occur.
When the used beverage containers were heated to
about or slightly above llOO~F, generally it was found tha-t
the M5182 ends sagged or slumped on the AA3004 can body.
However, when -~he containers were agitated at about this
-temperature by permitting them to drop from a conveyor belt,
for example, the lids were found to detach themselv~s from
the can bodies and were divided or fragmented in small
particles while ~he can bodies were relatively unchanged.
Agitation sufficient to detach the ends also may be effected
in a rotary furnace or kiln while the used cans are heated
to a temperature in the range of 1077 to about 1155F, wi~h
a preferred range being 1077 to 1130F an,d typically not
higher than 1120F. Agitation sufficient to remove the ends
in the rotary furnace can be that which occurs at these
temperatures when the cans are tumbled inside the furnace.
As noted hereinabove, forces such as obtained from hammering
or by the use of jaw crushers should not be used because
they act to flatten the cans or otherwise entrap the
fragmented ends with the can bodies. As no~ed earlier,
operating at temperatures high in the melting range can
result in too much li~uid metal and the attendant problems
therewith. The melting problem becomes particularly acute
if the used beverage cans are held for a relatively long
time at temperatures high in -the melting range. At
temperatures in the range of 1077 to 1130F, the time at
temperature can range from 30 seconds to less than 10
minutes.
In the classification step, the AA5182 fragments
can be separated from whole can bodies or from can bodies
which have been shredded by screening. However, it will be
appreciated that other methods of separation may be used,
all of which are contemplated to be within the purview of
the present invention.
In another aspect of the invention, it has been
found important to remove metal fines from the process.
That is, when it is found desirable to shred the aluminum
articles, e.g., used aluminum materials such as used
containers, it has been found that shredding results in the
generation of a significant amount of fine metal referred to
herein as fines. Normally, the generation of such fines
would not be considered to be a significant problem~
~lowever, when beverage containers are processed to separate
the lid.s from the container bodies, the lids are fragmen-ted
as noted herein, and have a size range substantiall~ smaller
than the bodies which permit separation therefrorn. However,
3 ~f ~5~
if th~ used materials, e.g., used beverage containers, are
shredded prior to processing for separation purposes, the
shredding can result in fines which are in the size range
constituting ~he lid fragments. The fines generated by
shredding ,in fact, can be said to contaminate the
fragmented por~ion. For example, if the beverage can is
constituted of 75 wto% AA3004 and 25 wt.% AAS182, the fines
generated on shredding a feedstock comprised of such
containers can have 93 wt.% of AA3004 and only 7 wt.%
AA5182. Thus, it will be seen that there is a great need to
prevent this type of contamination in the present process.
Omitting the step of removing the fines results then in the
fragmen~ed AA5182 portion being contamina-ted with AA3004
fines from the can bodies. Thus, it has been found that
removing fines in the size range corresponding to the size
range of the fragmen-ted portion being separa-ted from the
container body portion results in substantially fragmented
portions being substantially free of fines. The fines
should be removed after the shredding step and before
fragmenting step. One method of removing the fines can be
the use of screens, although other techniques 9 such as air
separation and the like, are contemplated within the purview
of the invention.
When the feedstock used is beverage containers
having, for example, AA3004 bodies and AA51~2 lids, af-ter
shredding, the fines can constitute 1 to 15 wt.% or more of
-the shredded feedstock.
In a test utilizing whole cans 9 the used beverage
containers were processed in a test apparatus at about
1110F. The fragmented end pieces were 25.3% of the
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delacquered can weight. The body parts represented 74.7%.
This sugges-ts that the aLloy separation was nearly 100%
effective, The two portions were melted and anal.yzed, The
spectrographic results appear in Table VIII which may be
compared ~o AA5182 and AA3004 (See Tables IX and X). These
analyses further support that 100% separation of the two
alloys is possible when the starting material is whole cans,
The following provides an example of the
contamination which can result from the fines generated by
shredding. From Table X, the composition range for
manganese in AA5182 is 0.20 to 0.50 wt.%. Normally,
manufacturers of AA5182 maintain the manganese composition
near the middle of this range, For purposes of the
following examples, it is to be assumed that manganese
concentration of 0.38% is desired.
If the process of shredding and subsequent
fragmentation is performed on 100 units of used beverage
containers, i-t has been found ln one instance that five
units of fines generated in the shredding step had a
manganese level of 1.10%, These are, therefore, composed
almost entirely of AA3004. The fragmentation step produced
20 units of AA5182 with a manganese level. of 0.38%. If
these 25 units are not separated but are collected together,
then the resulting manganese level can be calculated to be
0.52%. This requires significarlt dllution to produce metal
of 0.38% manganese.
Ln yet ano-ther example, if th.e process produces a
shredded product or feedstock tha-t contains appro~imately 9
wt.% fines, the manganese level of -this material is 1.05
wt.%. If these 9 units were collected in the fragtnented
portion to~ether with the 20 units of AA5182, the total 29
units would have a manganese level of 0.59 wt.%. Again,
this requires significant dilution with pure aluminum to
produce AA5182 having a manganese level of 0.3~ wt.%. Thus,
it can be seen that it is important to remove the fines
prior -~o their being commingled with the fragmented portion.
As further illustrative of the invention, used
beverage cans having AA300l~ bodies and AA51~2 lids thereon
were processed through a ro-tary-type kiln. Samples were
taken of ingoing and exiting ma-terial for the rotary kiln at
four different kiln set temperatures, as follows: 1060,
1080, 1100 and 1120~. Ingoing samples were taken which
weighed about 15 kg ~35 lb). Approximately six minutes
later, representing the residence time o used beverage cans
in the kiln, about 45 kg (100 lb) Gf e~iting material was
sampled.
Prior to entering the furnaces, bales of used
beverage cans were processed through a shredder. The
shredder in -the process of partially shredding most of the
cans, generates some used beverage can fines. In the
figures, the screen analyses of ingoing and exiting material
are compared at each kiln set temperature to determine the
degree to which end fragmentation occurs inside -the kiln.
This is recognized as a decrease in weigh-t of the coarser
fractions and an increase in weight of the finer fractions.
The U.S. Standard Screen sizes that were used to
fractionate the samples are listed i-n Table 1, together
with the Tyler mesh equivalents.
Samples of each size fraction were melted and
analyzed to monitor alloy partitioning and also -to measure
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~'~r~
the amount of tramp impurity pickup.
The chemical composition of a sample makes it
possible to calculate the relative amount of M 300~ and
AA5182 present. This is done by assuming that AA3004
contains 1.10% manganese and that AA5182 contains 0.38%
manganese. A melt of used beverage cans having a manganese
content of 0.92% can be shown to contain 75% of AA3004
material and 25% of AA5182 material. This calculation was
done for each exiting fraction at the four kiln temperatures
of the test. The amount of AA~182 calculated to be present
appears as the totally shaded por-tion on the bar graphs in
Figures 2-5.
Figure 2 shows the particle size distribution of
ingoing and exiting material while the kiln set temperature
was 1060F. The distribution of AA5182 in the exiting
material is also shown. The recorded temperature during the
sampling period ranged from 1030 to 1060F. The primary
feature in the figure is that very little difference is seen
in ~he size distribution of ingoing and exi~ing material.
It is also shown that the mix of AA5182 and AA3004 in the
coarser exiting fractions is approximately 25% and 75%,
respectively, which indicates that lid fragmentation did not
appear to be occurring at this temperature.
Table II shows the spectrographic analysis of the
metal found in each size fraction for both entering and
exiting material. Again, ingoing and exiting material for a
given size fraction appear to be very similar 3 except for
magnesium.
There does) however, appear to be a variation in
composition that is dependent on size fraction which
17 -
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~ 5 ~
suggests that the crushing step, prior to delacquering,
generates more body fines than end fines. The finer
fractions exhibit elevated manganese levels and decreased
ma~nesium levels when compared to the coarser fractions.
These finer fractions, therefore, appear to be richer in
AA3004 content than the coarser ones. Wi-th the can body
being thinner and accounting for a larger surface area of
the can than the end, it may be expected that in shredding
used beverage cans the body would produce more fines than
would the end. The decreasing magnesium content with finer
particle size may also reflect the increased magnesium
oxidation incurred when melting the smaller sized material
for analysis purposes. The -10 mesh material, both ingoing
and exiting, did not contain sufficient metallic material to
melt and produce a sa~ple for spectrographic analysis.
The data from samples taken while the kiln set
temperature was 1080F and 1100F appear in Figures 3 and 4
and Tables III and IV, respectively. These samples show
fragmentation of AA5182 lids inside the rotary l~iln.
Specifically, the amount of material present in the finer
mesh fractions in the exiting material is increased when
compared to the ingoing material~ and these fines have
compositions that show AA5182 enrichment. This trend is
more pronounced at 1100 than at 1080F.
The samples taken at 1120F show the strongest,
de~initive evidence for AA5182 fragmentation inside the
kiln. The two coarsest fractions have experienced a
significant weight reduction after passing thro-ugh the kiln
and the four finer fractions all show a significan-t weight
increase (E'igure 5). The compositions of the fractions
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{,~S~
(Table V) show that the coarser fractions are nearly
commercial grade composition o~ AA3004 and tha-t the finer
material is nearly the commercial grade composition of
AA5182. Comparing data for the 1060F and 1120F
experiments shows migration of AA5182 ~rom the coarse
fractions to the fine fractions~
Table V shows that metal :Erom the -10 mesh
fraction of the 1120F sample contains 0.50% silicon. This
is very significant since this fraction represents
approximately 30% of the AA5182 in the sys-tem. This
material was furthPr screened down to determine the
possibility o screening out the tramp silicon contaminants.
The results appear in Table VI. The tramp silicon
apparently migrates to the -20 mesh fractions. The -25 mesh
fraction contained such a large amount of non-metallic
material that it could not be melted to prepare a sample for
spectrographic analysis. Vis-ua] inspection revealed
significant quantities of glass and sand. Chemical analysis
of the -25 material appears in Table vI-r. This fraction
contains only about 56% metallic aluminum. I'he sand and
glass content is about 23 wt.%, and the tramp iron content
about 1.7 wt.%. Discarding all -20 mesh rnaterial, to
minimize tramp silicon and iron pickup, will contribute 2.2%
to the system loss. However, this material contributes
substantially to skim generation and should be removed prior
to melting for this reason.
- 19 -
'`5~
Table I
Screens Used to Fractionate the Samples
U.S. Standard Tyler Mesh
Screen Equivalent
2 inches 2 inches
1 inch 1 inch
0.5 inch 0.5 inch
0.265 inch 3 mesh
No. 4 4 mesh
No. 7 7 mesh
No. 10 9 mesh
No. 14 12 mesh
No. 18 16 mesh
No. 20 20 mcsh
No. 25 24 mesh
- 20 -
.~.2'r~
Table -LI
Chemical Analyses of In~oing (IN) and Exiting ~OUT) Material
For Each SLze Fraction. Kiln Set Temperature: 1060F
Screen Si Fe Cu _Mn _ M~
-~2"
IN 17 41 .11 .90 1.19
OUT 17 41 .11 .91 1.23
IN .17 .41 .11 .92 1.22
OUT .18 .40 .10 .86 1.20
1/2" .16 .38 .10 .85 1.72
OUT .16 .39 .11 .86 1.02
-1/2"+0.265"
IN .17 .41 .11 .gl 1.19
OUT .17 .40 .11 .92 .78
~0.265"+4
IN .21 .41 .12 1.00 .73
OUT .2l~ .42 .12 1.01 .78
-~+7
IN .37 .45 .14 1.06 .35
OUT .26 .45 .13 1.05 .68
-7+10
IN .24 .44 .13 1.06 .26
OUT .24 .48 .13 1.03 .54
-10*
IN
OUT
*Contained insufficient metal content for quantometer
analysis.
21 -
:~ t',t~ D~
Table III
Chemical Analyses o:E Sl.ze Fractions Exiting
-the Kiln at a Set Temperature: 1080F
Screen Si_ Fe _Cu Mn _ M~
-~2" .17 .39 .11 .95 .9~
-2"+1" .13 .39 .10 .911.05
-1"+1/2" .17 .39 .11 .gO1.10
-1/2"+0.265" .17 .39 .10 .871.03
-0.265"+4 .22 .38 .10 .831.63
-4+7 .18 .36 .09 .732.08
-7+10 .17 .32 .07 .602.70
-10 .23 .32 .11 .551.54
Table IV
Chemical Analyses of Size Fractions Exiting
the Kiln at a Set Temperature: 1100 F
Screen Si Fe Cu Mn Mg
~2" .17 .l~l .12 .94 .48
-2"-~1" .18 .42 .12 .97 .66
-1"-~112" .19 .42 .12 .98 .6~
-1/2'l~0.265".18 .41 .12 .9~ .56
-0.265'l+4 .17 .35 .09 .731.36
-4+7 .15 .30 .19 .562.57
-7+10 .15 .29 .06 .462.15
-10* - - - - -
- 22 -
Table V
Chemical Analyses of Size Fractions Exiting
the Kiln at a Set Temperature: 1120F
U S
Screen Si Fe Cu Mn M~_
__ .___
-~2" .~9 .~4 .13 1.05 .58
-2"+1" .18 .43 .12 1.02 .66
~ 1/2l' .18 .44 .12 1.03 .67
-1/2"+0.265" .18 .43 .12 1.02 .57
0.265"+4 .21 .37 .10 .82 1.61
-4+7 .17 .30 .07 .52 2.97
-7+10 .1~ .25 .05 .36 3.43
-10 .50 .29 .07 .36 3.35
Table VI
Chemical Analyses of Fractions Resulting From
Further Fractionation of the Minus 10 Material
Exiting ~he Kiln at Set Temperature 1120F
U.S.
Screen wt % Si Fe Cu Mn M~
-10-~14 2.6 .15 .27 .0~l .38 3.67
-14+18 1.9 .16 .28 .04 .38 3.82
-18+20 0.5 .21 .26 .04 .35 3.64
-2G+25 0.4 .35 .21 .05 .33 3.74
-25* 1.8 - - - - -
*Contained insufficient metal content for quantometer
analysis.
- 23 -
5~
Table VII
Analysis of Minus 25 Material. Exiting
the Kiln at a Set Ternperature: 1120F
% Aluminum by Hydrogen Evolution 56.2%
Chemical Analysis: Al 56.7%
Fe 1.74%
Si 10.8%
Calculated SiO2 23.1%
% Magnetic Material 1.87%
X-ray Diffraction: Aluminum ~10%
Quartz ~10%
MgO ~ 10%
Unidentified e 10%
- 24 -
J ~
Table VIII
Chemical Analyses from Whole Can Experimen-t
Having 3004 Bodies and 5182 Ends
End Fra~ments Body Parts
Si O.lO 0.19
Fe .25 .40
Cu .03 .14
Mn .36 l.09
Mg 3.69 .7
Cr .02 ~Ol
Ni .00 .00
Zn .02 .04
Ti .Ol .02
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Various modifications may be made in the invention
without departing from the spirit thereof, or the scope of
the claims, and therefore, the exact form shown is -to be
taken as illustratlve only and not in a llmiting sense, and
it is desi.red that only such limita-tions shall be placed
thereon as are imposed by the prior art~ or are specifically
set forth in the appended claims.
- 27 -
